Safety device for roller levelers



Jan. 11, 1955 cozzo 2,699,196

SAFETY DEVICE FOR ROLLER LEVELERS Filed Feb. 23, 1952 INVENTOR.

i GIQJ'EPIE Cb ZO Wan/W United States Patent SAFETY DEVICE FOR ROLLERLEVELERS Giuseppe Cozzo, Yonkers, N. Y., assignor to Hydropress,

Incorporated, New York, N. Y., a corporation of Delaware ApplicationFebruary 23, 1952, Serial No. 273,028

9 Claims. (Cl. 153-87) The present invention relates generally to rollerlevelers, and is particularly directed to. safety devices for preventingoverloading of such machines.

In manufacturaing metal sheets and strips of relatively wide and thinmaterial, it is customary to straighten the sheets or strips by passingthem through a machine, known as a roller leveler, which comprises alarge number of upper and lower working rolls for imparting a series ofbends to the material. So long as the sheets or strips to bestraightened are of uniform thickness and pass through the rollerleveler without incident, the spacing or clearance between the upper andlower rolls may be adjusted to accommodate the sheets or strips and nooverload conditions need be encountered. However, in manufacturing metalsheets and strips, variations in the thickness thereof are unavoidableso that, from time to time, a sheet or strip portion of excessivethickness may be passed between the rolls of the roller leveler therebycausing excessive strains on the leveler structure and overloading themotor driving the rolls. Similar overloading of the roller leveler mayresult from the passage through the latter ofa sheet or strip portionwhich is folded over or which'jams between the working rolls for anyreason whatsoever.

Accordingly, an object of the present invention is to provide a safetydevice in association with a roller leveler for halting the operation ofthe latter whenever an overload condition is encountered.

Another object is to provide a safety device associated with a rollerleveler having working rolls driven, through intermediate drive shaftmeans, by an electric motor orother similar source of motive power,wherein safety device means, associated with one or more drive shafts ofthe drive shaft means,- respond to the torsional load on its drive shaftto halt the motor, and thereby stop the roils when the torsional loadexceeds a predetermined safe va ue.

A further object is to provide a safety device associated with a rollerleveler having working rolls driven, through intermediate drive shaftmeans, by an electric motor or other similar source of motive power,wherein the safety device responds to excessive torsionaldeflection of adrive shaft of the drive shaft means caused by torsional overloading of;the shaft to automatically halt the motor andthereby stop-rotation ofthe working rolls.

A still further object of-the present invention is to provide a safetydevice of the described character which is simple in its operationandconstruction and is adapted to be associated with existingrollerlevelers or similar machines without requiring any substantialrevision .or alteration thereof.

In accordance with the present invention, the above and other objects,features and advantages appearing in the following detailed descriptionare obtained by providing a safety device including two mutuallyengageable contacts fixed to the drive shaft of the roller leveler ataxially spaced apart locations of the shaft and arranged to contact eachother when the portion of the shaft between the axially spaced apartlocations undergoesa predetermined torsional deflection corresponding toan overload condition in the roller leveler. The two contacts on thedrive shaft are interposed in a suitable control circuit which isoperative .to halt the motor coupled to the drive shaft when thecontacts engage each other.

In one aspect of the invention a safety device can be connected with thesecond roller contacting the sheet after the sheet enters the rollerleveler. When the roller 2,699,196 Patented Jan. 11, 1955 leveler isreversible, a safety device appropriately constructed can be connectedin the drive to the second roller contacting the sheet when the machineis reversed.

A11 illustrative embodiment of the present invention will now bedescribed in connection with the accompanying drawing forming a parthereof, and wherein:-

Fig. l is a diagrammatic perspective view of a safety device embodingthe present invention and shown in association with a roller leveler;

Fig. 2 is a side elevational view of the safety device of Fig. l withthe electrical connections and equipment for controlling the operationof the roller leveler motor being shown diagrammatically;

Fig. 3 is a transverse sectional view taken along line 33 of Fig. 2 andshowing the disposition of parts of the safety device during normaloperation; and

Fig. 4 is a view similar to Fig. 3, but showing the disposition of partsof the safety device when the associated roller leveler has beenoverloaded.

Referring to the drawing in detail, and initially to Fig. 1 thereof, aseries of working rolls 11, 12, 13, 14, 15, 16 and 17 form parts ofa'roller leveler of conventional construction, illustration of theremainder of the conventional leveler being avoided for the purpose ofclarity. Various numbers of upper and lower rolls can be used. Thesuccessive upper and lower working rolls 11 to 17, inclusive, arearranged so that a sheet or strip S of relatively thin metal or othermaterial, when passed between the rolls in the direction of the arrow Ain Fig. 1, has a series of alternately oppositely directed bendsimparted thereto so that the sheet or strip is straightened in a wellknown manner upon emergence from the roller leveler. In order to effectmovement of the sheet or strip S through the working rolls, the upperrolls and lower rolls are rotated in opposite directions through a gearbox assembly generally indicated by the numeral 22, and shaftsschematically indicated by dot-dash lines 21. The gear assembly isdriven by an electric motor 19 or any other suitable source of motivepower.

The second roll in contact with the sheet after it enters the leveler isthe roll which may be overloaded due to the conditions mentionedpreviously so that a safety device is needed in its drive.

In the illustrated embodiment, the shaft of upper roll 16 has a safetydevice 18A therein, this roll being the second roll contacted by thesheet when the sheet is moving in the direction indicated by the arrowA. When the sheet is moving in the direction shown by the arrow B, roll12 is the second roll contacted so that a safety device indicatedgenerally by 18B is located in its drive shaft. The safety device 18A isspecifically shown in Figs. 2, 3 and 4 and will be describedhereinafter, safety device 188 being the reverse of device 18A. Shaft 20of roll 16 is coupled, preferably by a conventional universal joint 24,to one end of a metal shaft section 25 which forms a part of theassembly 18A and is connected at its other end to the shaft 26 of gearbox 22 by a suitable coupling 27. Operation of the motor 19 effectsrotation of the roll 16 through the connected shafts 26, 25 and 20.Upper rolls 12 and 16 are rotated in a direction corresponding tomovement of the sheet S, such being in one direction when the sheet ismoving as indicated by the arrow A and in the opposite direction whenthe sheet moves as indicated by the arrow B. Other arrangements of drivecan be used and safety devices employed and located as required by theparticular arrangement of rolls involved. For example, there may be twomore rolls on the upper level making five rolls on top and four rolls onthe bottom. In such a case, the second roll to be contacted will be theroll at either end of the bottom group of rolls according to thedirection of movement of the sheet. The safety devices then would belocated in the drives of said lower end rolls.

So long as the sheet or strip S is of uniform thickness,

r the spacing or clearance between the upper rolls 12, 14

and 16 and the corresponding lower rolls 11, 13, 15 and 17 may beadjusted to accommodate such thickness so that the sheet or strip maypass between the rolls and be straightened without overloading orexcessively straining the structure of the roller leveler or the drivingmotor. However, when the thickness of the sheet or strip is nonuniformand excessive in certain places, a condition that cannot always beavoided in its manufacture, so that the sheet or strip jams betwen therolls, or when such jamming occurs for any other reason, for example,because the sheet or strip is folded over, the structure of the levelerand the driving motor will be overloaded and damage to the machine willresult unless its operation is immediately halted.

In order to effect the automatic cessation of operation of the rollerleveler when an overload condition is encountered, the present inventionprovides a safety device in association with the shaft section andsensitive to excessive torsional deflection of the latter caused bytorsional overloading of the shaft to operate a control circuit forinterrupting or reversing the supply of electric current to the motor19. The illustrated safety device embodying the present inventionincludes two confronting and normally spaced apart contacts, generallyindicated by the numerals 28 and 29 (Fig. 2), which are fixed to shaftsection 25 as axially spaced apart locations on the latter so that thecontacts are brought together when the portion of shaft section 25between these axially spaced locations is torsionally deflected througha predetermined angle a (Fig. 4).

As seen in Figs. 2, 3 and 4, contact 28 is mounted on a support assemblywhich includes a cylindrical collar 30 having a greater inner diameterthan the diameter of shaft section 25 and an axially extending supportmember 31, preferably of semi-cylindrical configuration, formedintegrally with collar 36 and having a lug 32 projecting radially fromits free end portion adjacent a side edge thereof to carry contact 28.The collar 39 and support member 31 are formed of metal, preferablyhaving good electric conducting characteristics, and collar 30 engagesaround shaft section 25 adjacent one end of the latter and is spacedfrom the shaft section by a sleeve 33 of suitable insulating material.Collar 30 is fixed to shaft section 25 by suitable fastenings 34 whichare electrically insulated from either the shaft section or the collarso that the support assembly for contact 28 is electrically insulatedfrom the shaft section with the support member 31 extending axiallyalong the shaft section and spaced from the latter.

Contact 28 consists of a contact screw 35 threadedly extending throughlug 32 for adjustment purposes and having a locking nut 36 thereon forretaining the contact screw in selected position relative to the lug.

The other contact 2? is formed by a metal plate 37 secured to shaftsection 25 by suitable fastenings 38 at a location on the shaft sectionadjacent lug 32 of the support assembly for contact 28, plate 37 beingin electrical contact with shaft section 25. A contact lug 39 extendslaterally from plate 37 and confronts contact screw 35 of contact 28. Itshould be noted that the surface of contact lug 39 confronting contactscrew 35 faces in the direction of rotation of shaft section 25, asindicated by the arrow of Fig. 4, so that torsional deflection of theshaft section, between the locations at which collar 30 and plate 37 aresecured thereto and resulting from resistance of the rolls 16 and 17 tothe rotation imparted by motor 19, causes the contact screw 35 and lug39 to be relatively displaced towards each other. Adjustment of thecontact screw 35 to vary the distance it projects through lug 32 towardscontact lug 39 varies the angle a of torsional deflection of shaftsection 25 necessary to bring the contact screw and contact lug intomutual engagement.

Contacts 28 and 29 constitute a normally open switch assembly rotatingwith the shaft section 25 and closing when an overload on the lattercauses a predetermined torsional deflection thereof. In order to connectthe switch assembly, constituted by contacts 28 and 2?, into a controlcircuit, slip rings 49 and 41 are provided on shaft section 25 and arerespectively engaged by stationary brushes 42 and 43. Slip ring 40 is inelectrical contact with shaft section 25 and hence communicateselectrically with contact 29, while ring 41 is insulated from shaftsection 25, for example, by the sleeve 33, and is electrically connectedto collar 30 for electrical communication with contact 28.

The control circuit for motor 19 is shown schematically and includesrelays 44 of conventional construction which are connected to brushes 42and 43 so that the relays are energized when contacts 28 and 29 engage.Relays 44 are arranged to control a conventional motor starter assembly45 so that the supply of current from the lines 46 to motor 19 isinterrupted when the relays 44 are energized by closing of the contacts28 and 29. After the operation of the motor has been halted by closingof contacts 28 and 29 to stop rotation of the working rolls, theoperation of the roller leveler can only be resumed by manual actuationof the starting switch, not shown, included in the motor starterassembly. Merely by way of example, relay arrangement 44 may have asolenoid 50 which will be energized from leads 50a and 5012 by closingcontacts 35 and 39. Upon energization switch blade 51 will be closed tofurnish power from leads 52 to solenoid 53. Starter assembly 45 may takethe form, for example, of an arrangement having blade 54 pivoted at 55with a secondary pivot blade 56. Blade 56 is shown engaged with contact57. Blade 56 is held in the position illustrated by engagement of thelatch 53 with pin 59 thereon, latch 58 being pivoted at its cornerSpring 61 tends to urge blades 54 and 56 together. Lines 46 furnishpower to motor 19. Line 46A is connected through the resistance 61A tothe motor. There is a conventional holding magnet 62 for holding theblade 54 in running position after it is manually moved to the right.Solenoid 53 has a. plunger arranged so that when the solenoid isenergized the plunger will pivot latch 58 counter clockwise so as torelease blade 56. When this is done, spring 61 will pull the blade 56upwardly and break the circuit to motor 19. Solenoid 53 is energizedwhen switch blade 51 is pulled against contact 62 upon energization ofsolenoid 50.

The safety device 18B is generally similar to safety device 18A with theexception that it is arranged to operate in the reverse directionbecause roll 12 turns in a direction reverse to that just described whensheet S moves in the direction of the arrow B. Operation of device 18Bin this reverse direction is achieved by reversely arranging theelements 28, 29' and 31 thereof relative to the corresponding elementsof safety device 18A.

From the above description of an illustrative embodiment, it is apparentthat the present invention provides a safety device in association witha roller leveler which acts in response to an overload condition, asindicated by a predetermined torsional deflection of the drive shaft, tohalt the operation of the leveler so that damage to the latter will beprevented in the event that material being passed through the rollerleveler causes jamming or excessive resistance to rotation of theworking rolls. Since the contacts 28 and 29 are merely applied to asection of the shaft driving the rolls of the roller leveler, it isapparent that safety devices embodying the present invention may beapplied to existing roller levelers with- ?ut requiring substantialrevision or alteration of the atter.

While an illustrative embodiment of the invention has been set forth indetail in the foregoing description and in the accompanying drawing, itis to be understood that the invention is not limited to that preciseembodiment,

and that changes and modifications, apparent to one skilled in the art,may be effected therein without departing from the scope of theinvention.

What is claimed is:

1. In combination with a roller leveler having working rolls, a driveshaft operatively connected to at least one of said rolls and means forrotating said drive shaft; a safety device comprising two confrontingand normally spaced apart contacts on said drive shaft for movementtowards each other in response to torsional deflection of said shaft,and electrical means operatively connected to said contacts andcontrolled by the latter to render 1 said shaft rotating meansinoperative when said contacts are mutually engaged.

2. In combination with a roller leveler for straightening sheets of thinmaterial and including working rolls, a drive shaft operativelyconnected to at least one of said rolls and an electric motor forrotating said drive shaft; a safety device comprising two confrontingand normally spaced apart contacts on said drive shaft for movementtowards each other in response to torsional deflection of said shaft,and electrical means operatively connectedto said contacts andcontrolled by the latter to render said motor inoperative when saidcontacts are brought together by a predetermined torsional deflection ofsaid shaft caused by overloading of said roller leveler.

3. In combination with a roller leveler for straightening sheets of thinmaterial and including working rolls,

a drive shaft operatively connected to at least one of said rolls, anelectric motor for rotating said drive shaft, and means for controllingthe supply of electric current to said motor; a safety device comprisingtwo confronting and normally spaced apart contacts, means mounting saidcontacts on said drive shaft at axially spaced apart locations on thelatter so that said contacts move towards each other in response totorsional deflection of the portion of said shaft between saidlocations, and electrical means controlled by said contacts andoperatively connected to said current supply controlling means tointerrupt the supply of current to said motor when said contacts arebrought together by a predetermined torsional deflection of said portionof the drive shaft caused by overloading of said roller leveler.

In combination with a roller leveler for straightening sheets of thinmaterial and including working rolls, a drive shaft operativelyconnected to at least one of said rolls, and means for rotating saiddrive shaft; a safety device comprising two confronting contacts, meanssupporting said contacts on said drive shaft for movement relative toeach other in the direction circumferentially of said shaft, saidsupporting means including means securing said contacts to said shaft ataxially spaced apart locations on the latter so that said contactsrotate with said shaft and move circumferentially relative to each otherin response to torsional deflection of the portion of the shaft betweensaid spaced apart locations, and electrical means including a circuithaving said contacts interposed therein for rendering said shaftrotating means inoperative in response to a predetermined torsionaldeflection of said portion of the drive shaft caused by overloading ofsaid roller leveler.

5. In combination with a roller leveler for straightening sheets of thinmaterial and including working rolls. a drive shaft operativelyconnected to at least one of said rolls, and means for rotating saiddrive shaft; a safety device comprising two contacts, a first supportfixed to said drive shaft and supporting one of said contacts adjacentthe periphery of said shaft, a second support fixed to said drive shaftat a point spaced axially from the point on said shaft at which saidfirst support is fixed to the latter, said second support extendingaxially along said shaft toward said one contact and supporting theother of said contacts adjacent the periphery of said shaft and in aposition confronting said one contact so that said contacts aredisplaced circumferentially relative to each other in response totorsional deflection of the portion of the drive shaft between thepoints at which said first and second supports are fixed thereto, andelectrical means including a circuit having said contacts interposedtherein for rendering said shaft rotating means inoperative in responseto a predetermined torsional deflection of said portion of the driveshaft caused by overloading of said roller leveler.

6. In combination with a roller leveler for straightening sheets of thinmaterial and including working rolls, a drive shaft assembly operativelyconnected to at least one of said rolls and having an elongated shaftsection, and means for rotating said drive shaft assembly; a safetydevice comprising first and second contacts, first support means fixedto said shaft section adjacent one end of the latter and supporting saidfirst contact adjacent the periphery of said shaft section, secondsupport means fixed to said shaft section adjacent the other end of thelatter and supporting said second contact adjacent the periphery of saidshaft section and in a location axially of said shaft sectionconfronting said first contact so that said first and second contactsrotate with said shaft section and are displaced circumferentiallyrelative to each other in response to torsional deflection of said shaftsection, first and second slip rings on said shaft section andelectrically connected to said first and second contacts, respectively,and electrical means including brushes engaging said slip rings and acircuit having said brushes connected therein for rendering said shaftro tating means inoperative in response to a predetermined torsionaldeflection of said shaft section caused by excessive resistance torotation of said working rolls.

7. In combination with a roller leveler for straightening sheets of thinmaterial and including working rolls between which the sheets arepassed, a drive shaft assembly operatively connected to at least one ofsaid rolls and having an elongated shaft section of electricallyconducting material, and means for rotating said shaft assembly; asafety device comprising first and second contacts, first support meansfixed to said shaft section adjacent one end of the latter and inelectrical contact therewith, said first support means supporting saidfirst contact adjacent the periphery of said shaft section, secondsupport means fixed to said shaft section adjacent the other end of thelatter and extending axially of said shaft section to support saidsecond contact adjacent the periphery of said shaft section and in aposition confronting and normally spaced circumferentially from saidfirst contact so that torsional deflection of said shaft section causesrelative movement of said first and second contacts toward each other,said second support means being formed of an electrically conductingmaterial, insulating means electrically isolating said second supportmeans from said shaft section, first and second slip rings on said shaftsection electrically connected to said shaft section and to said secondsupport means, respectively, insulating means electrically isolatingsaid second slip ring from said shaft section, brushes respectivelyengaging said first and second slip rings, and electrical meansincluding a circuit having said brushes interposed therein for renderingsaid shaft rotating means inoperative when said first and secondcontacts are brought together by torsional deflection of said shaftsection caused by excessive resistance to rotation of said workingrolls.

8. The combination as set forth in claim 7; wherein said second supportmeans includes a support member having a cylindrical portion surroundingand spaced from said shaft and an axial extension integral with saidcylindrical portion and formed with a radially projecting lug, andwherein said second contact includes a contact screw threadedlyextending through said lug for adjustment toward and away from saidfirst contact to thereby vary the torsional deflection of said shaftsection required to bring together said first and second contacts.

9. In combination a drive shaft for rotating the working parts of amachine, a motor connected to said drive shaft for rotating the latter,two circumferentially confronting contacts carried by said shaft,support means fixing said contacts to said shaft at axially spaced apartlocations on the latter so that said contacts are displacedcircumferentially relative to each otther in response to torsionaldeflection of the portion of the drive shaft between said locations onthe latter, and electrical means connected to said motor including anelectric circuit having said contacts interposed therein and effectiveto render said motor inoperative in response to a predeterminedtorsional deflection of said portion of the shaft caused by excessiveresistance to rotation of the working parts of the machine.

References Cited in the file of this patent UNITED STATES PATENTS1,040,863 Blaxter Oct. 8, 1912 2,068,260 Biggert, Ir. Jan. 19, 19372,144,769 Melmer Jan. 24, 1939 2,281,432 Grohn Apr. 28, 1942 2,389,098Welch Nov. 13, 1945 2,422,905 Jackson June 24, 1947 FOREIGN PATENTS560,041 Great Britain Mar. 16, 1944

